Circuit configuration for an anti-lock-controlled brake system

Abstract

This is a circuit configuration provided for an anti-lock-controlled brake system and serving for processing sensor signals obtained by wheel sensors (5) and for generating braking pressure control signals. This circuit configuration contains two microcontrollers (1, 2) interconnected by data exchange lines (7). The handled signals are concurrently processed by the microcontrollers independently of one another and the exchanged signals are checked for consistency. A deviation of the exchanged signals which is due to malfunctions is signalized to a safety circuit (8) which, thereupon, interrupts the power supply to the solenoid valves (Ll . . . Ln). The monitoring signal (WD1, WD2) fed to the safety circuit (8) is a predetermined alternating signal in case of consistency of the exchanged signals and in case of proper operation of the circuit configuration. The safety circuit (8) compares the alternating signal with a time standard derived from a clock generator (TG2, TG3) which is independent of the operating cycle (TG1) of the microcontrollers (1,2). A change in the alternating signal, as well as a failure in the time standard, causes a cut-off of power supply and, hence, of anti-lock control.

What is claimed is: 
     
       1. A circuit for controlling a vehicle anti-lock system operative to receive wheel condition signals from a plurality of wheel condition sensors and generate brake pressure signals in response thereto to modulate vehicle brake line solenoid valves, said circuit comprising: first microcontroller means and second microcontroller means interconnected by data exchange lines. (a) said first microcontroller means for: (1) receiving selected ones of said wheel condition signals,   (2) independently processing said wheel condition signals received by said first microcontroller means,   (3) generating said brake pressure signals in response to said wheel condition signals received by said first microcontroller means,     (b) said second microcontroller means for: (1) receiving selected ones of said wheel condition signals,   (2) independently processing said wheel condition signals received by said second microcontroller means,   (3) generating said brake pressure signals in response to said wheel condition signals received by said second microcontroller means,     (c) said first microcontroller means also for: (1) receiving from said second microcontroller means at least one of: (i) said selected wheel condition signals received by said second microcontroller means, and   (ii) said brake pressure signals generated by said second microcontroller means, and     (2) comparing signals received from said second microcontroller means with corresponding signals received and generated by said first microcontroller means, and   (3) generating a first monitoring signal as a function of any difference between compared signals, said first monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level, and     (d) said second microcontroller means also for: (1) receiving from said first microcontroller means at least one of: (i) said selected wheel condition signals received by said first microcontroller means, and   (ii) said brake pressure signals generated by said first microcontroller means, and     (2) comparing signals received from said first microcontroller means with corresponding signals received and generated by said second microcontroller means, and   (3) generating a second monitoring signal as a function of any difference between compared signals, said second monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level, and and safety circuit means for:         (a) comparing each of said first and said second monitoring signals with a time standard from at least one clock generator operating independently of an operating cycle of said first microcontroller means and said second microcontroller means, and   (b) disabling said solenoid valves whenever any of said first and said second monitoring signals exceeds said predetermined threshold level.   
     
     
       2. A circuit according to claim 1 further including a trigger circuit through which said wheel condition signals are conducted to said first and said second microcontroller means and containing a first clock generator for said first monitoring signal operating independently of an operating cycle of said first microcontroller means and a second clock generator for said second monitoring signal operating independently of an operating cycle of said second microcontroller means. 
     
     
       3. A circuit according to claim 2 further including: (a) a power supply,   (b) means for selectively conducting power from said power supply to said solenoid valves to actuate said solenoid valves, and   (c) valve control means responsive to said safety circuit means for preventing actuation of said solenoid valves.   
     
     
       4. A circuit according to claim 3 further including second valve control means responsive to said safety circuit means for preventing actuation of said solenoid valves. 
     
     
       5. A circuit according to claim 4 further including amplifying means between said first and said second microcontroller means and said solenoid valves, and said second valve control means control said amplifying means. 
     
     
       6. A circuit according to claim 5 further including monitoring circuit means for: (a) developing control signals representative of defects in said anti-lock system, and   (b) supplying said control signals to said first and said second microcontroller means and wherein said first and said second monitoring signals indicate the presence of said control signals.     
     
     
       7. A circuit according to claim 6 wherein said monitoring circuit means include a parity chain responsive to operation of said solenoid valves and said brake pressure control signals. 
     
     
       8. A circuit according to claim 1 wherein each of said first and said second monitoring signals is compared with a separate time standard from a separate clock generator operating independently of an operating cycle of said first microcontroller means and an operating cycle of said second microcontroller means. 
     
     
       9. A circuit for controlling a vehicle anti-lock system operative to receive wheel condition signals from a plurality of wheel condition sensors and generate brake pressure signals in response thereto to modulate vehicle brake line solenoid valves, said circuit comprising: signal processing circuit means for:   (a) receiving said wheel condition signals, and   (b) generating said brake pressure signals in response to said wheel condition signals, said signal processing circuit means including:     (a) first microcontroller means for: (1) receiving selected ones of said wheel condition signals,   (2) independently processing said wheel condition signals received by said first microcontroller means, and   (3) generating said brake pressure signals in response to said wheel condition signals received by said first microcontroller means, and     (b) second microcontroller means for: (1) receiving selected ones of said wheel condition signals,   (2) independently processing said wheel condition signals received by said second microcontroller means, and   (3) generating said brake pressure signals in response to said wheel condition signals received by said second microcontroller means, and     (c) data exchange means interconnecting said first and said second microcontroller means for exchanging between said first and said second microcontroller means at least one of: (1) said selected wheel condition signals, received by said first and said second microcontroller means, and   (2) said brake pressure signals generated by said first and said second microcontroller means, and     (d) said first microcontroller means also for: (1) comparing signals received from said second microcontroller means with corresponding signals received and generated by said first microcontroller means, and   (2) generating a first monitoring signal as a function of any difference between compared signals, said first monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level,     (e) said second microcontroller means also for: (1) comparing signals received from said first microcontroller means with corresponding signals received and generated by said second microcontroller means, and   (2) generating a second monitoring signal as a function of any difference between compared signals, said second monitoring signal being an alternating signal having a predetermined frequency and amplitude whenever the difference between compared signals falls below a predetermined threshold level,     and safety circuit means, including at least one clock generator operating independently of an operating cycle of said first microcontroller means and an operating cycle of said second microcontroller means, for:   (a) comparing each of said first and said second monitoring signals with a time standard from said clock generator, and   (b) disabling said solenoid valves whenever any of said first and said second monitoring signals exceeds said predetermined threshold level.   
     
     
       10. A circuit according to claim 9 wherein said safety circuit means include two clock generators each operating independently of an operating cycle of said first microcontroller means and an operating cycle of said second microcontroller means and said first monitoring signal is compared with a first time standard from said first clock generator and said second monitoring signal is compared with a second time standard from said second clock generator.